Preheat oven to 350°F. Place your pie crust in a 9” pie plate and crimp the edges as desired. Chill until dough is ready.
Cream butter, peanut butter, and both sugars in the bowl of an electric mixer fitted with the paddle attachment, about 2-3 minutes. Add egg, vanilla, milk, and salt and mix until combined. Slowly add flour and mix until dough just comes together. Stir in chocolate chips and chopped candy pieces. (I used Kit Kat and Butterfingers.)
You can also use a hand mixer for this recipe, if you prefer.
Press cookie dough into the prepared pie crust. Press additional candy on the top, if desired. (I pressed more chocolate chips, Butterfingers, Kit Kats, and Rolos on top.)
Cover edges of the pie with a pie shield or strips of foil. Bake for about 35-45 minutes, removing the pie shield about 10 minutes prior the pie finishing baking.
Cool completely before slicing and serving. Serve it room temperature or warm, plain or with ice cream or whipped cream.
Store covered for up to 3 days or slice and freeze for up to one month.